CLAUSTRA ALPIUM IULIARUM
Aleksander J. Potocnik
The Great Roman Fortified War Zone
CLAUSTRA ALPIUM IULIARUM
The remnants of the Ad Pirum fortress.
In year 6 the rebellion in Dalmatia faced Rome with the need to control the passage between it's eastern and Western part. So Rome start fortifying the area where Alps descend to the Adriatic sea, making it the thinnest part of the empire. By the fourth century the fortifications evolved into an independent administrative zone secured by an extensive system of forts and defensive walls called "limes". It's centre was fortress Ad Pirum. Today the name of this location is Hrusica (the Pear Hill) and is believed to derive from the Roman name. But most likely the Roman name Ad Pirum originates not in pear but in a Greek expression for a fire, indicating that an older signalling station my have been situated on this site.
The main arch of walls and forts was spreading between Cedad (Cividale, roman Forum Iuli) and Rijeka (Roman Tarsatica), following the valley of the Idrijca river, the brim of hills south of Ljubljana (Roman Aemona) and above the Kocevje hollow and turning south through the present day wilderness of Gorski Kotar region to reach the sea at Rijeka.
There were also some in-depth fortifications along the main road, starting at present day Vrhnika (Nauportus) and ending at Ajdovscina (Roman Castra) that was itself a fort. It's central fort Ad Pirum (present day Hrusica), built on the 858 metres high pass had a permanent crew of 500 men, but was able to host up to 100.000 soldiers, which makes it a formidable military post. It's walls were as thick as two metres, eight metres high with ten metres high towers.
It was unearthed by Austrian and conserved by Italian archaeologist before the second world war. The burghus at Lanisce, as part of the Roman limes - the block wall, was restored by Slovenian archaeologists in seventies.
Ironically these fortifications mostly demonstrated their usefulness during the civil struggles rather than invasions. Apart of small skirmishes and Markoman onslaught in 169 the zone has seen two major battles that ended throne contests. In 351 Konstancius concluded the fight against his rival Magnecius by taking Ad Pirum. But the most important event with effects reaching as far as the present day was the battle of the Cold River (Fluvius Frigidus) between Castra and Ad Pirum in 394. The emperor of the eastern part of the empire Theodosius, who favoured Christianity, defeated the western pretendant Eugenius, thus establishing Christianity as the main religion of the continent.
Between 5th and 12th centuries the area become abandoned. After twelfth century the old Roman route comes to life again, but not the fortifications that are by now completely overgrown by forest. Visitors will find restored sections rather attractive, while other sections can be spotted only by a well trained eye.
The restored Burghus at Lanisce near Hrusica.
Roman Castra, present day the city of Ajdovscina.
Remnants of once mighty walls of Ad Pirum.
©a¼el Jaro: Ad Pirum, Rimska ¼tabna baza na Hru¼ici, Ljubljana 1988
Osmuk, Svolj¼ak, Æbona-Trkman: Ajdov¼Ëina - Castra, Ljubljana 1994
Vuga Davorin: Vipavska dolina, Ljubljana 1984
Vasle Branko: Slovenija v Ëasu in prostoru, Ljubljana 2000
fotografije in risbe: S. A. JankoviË
The overview of fortifications in Alpe-Adria regions.
ARS CARTAE pictorial maps gallery
of Alpe-Adria regions (Slovenia, NE Italy, Croatia...)
Site design: A.J. Potocnik
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